Northern Waterthrush

Our two species of waterthrushes, although warblers rather than thrushes, are at least closely tied to water. The Northern is the more common and widespread of the two, and during the breeding season is found in wooded and shrubby swamps with at least some standing water. Here they forage in shallow water like a shorebird, pecking at insects and other small prey on the surfaces of rocks and twigs, and probing into mud or wet leaves. Their characteristic bobbing motion is also like that of some sandpipers and may serve to startle prey into motion so they can be more easily seen and captured.

In the winter Northern Waterthrushes retain their preference for forested wetlands and can be especially common in mangroves along Caribbean and Central American coastlines. Densities in these habitats can be quite high depending on water levels, with the fewest birds when water is very high or very low. Research on winter ground populations has demonstrated that Northern Waterthrushes will shift their winter ranges by as much as a few kilometers as they track good foraging conditions. A different study showed that they leave their daytime feeding areas at dusk and travel equally large distances to spend the night in communal evening roosts. Climate change may threaten these coastal forests so critical to Northern Waterthrushes in the winter, and they are also susceptible to coastal development.

The two waterthrushes are extremely similar in appearance and behavior, but with a good look can usually be told apart. The key features are the underparts and eye-stripe, which are tinged buffy in Northerns and pure white in Louisianas. The Northern’s eye-stripe is narrower and doesn’t get wider towards the rear. Habitat is of course another important clue, since Northerns are rarely found along the shaded forest streams preferred by their southern cousins.